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AABP COVERAGE

Partial debut of antimicrobial decision system planned for spring

By Susan C. Kahler

Posted Nov. 1, 2004

An AABP general session audience listened intently as Dr. Mike Apley previewed and traced the progress of the Veterinary Antimicrobial Decision System he and collaborators are developing, showing slides describing some of the disease-specific monographs. Working with him on the project are Drs. Cory Langston, Jeff Wilcke, and Virginia Fait.

VADS will be a peer-reviewed decision support system centered on therapeutic antimicrobial applications. Food supply veterinarians and students can subscribe to the Internet database to access analyses of published data to support construction of antimicrobial dosing regimens.

Using the best available pharmacokinetic and pharmacodynamic information, the VADS system collaborators are modeling the dosing regimens that would address bacteria with various minimum inhibitory concentrations. The system is designed to be transparent about how dosages were calculated.

Dr. Apley, an associate professor in the Department of Veterinary Diagnostic and Production Animal Medicine at the Iowa State University College of Veterinary Medicine, talked about the system subsequent to the AABP conference.

"We fully realize that without clinical trials, we can't say yes, something will definitely work or not work, but we feel we can help veterinarians avoid some unreasonable regimens," Dr. Apley said.

During his presentation, Dr. Apley gave an example of what the VADS modeling suggests would be an inadvisable regimen. Practitioners who initiate a once-daily dosage regimen of ampicillin trihydrate at the upper end of the label dosage range in cattle are likely not achieving sustained serum concentrations required to address a serious gram-negative bacterial infection. Salmonella and Escherichia coli isolates routinely cultured at veterinary diagnostic laboratories suggest that an MIC compatible with such a regimen would resolve few such infections encountered in veterinary clinics.

The VADS system should reveal areas where research is needed. Dr. Apley is assembling all clinical trial data he can find for the database, but in some areas, not many exist. "Where we don't have clinical trial data, it's our best estimate of what would be a reasonable starting point for veterinarians," he said.

Some areas will be difficult to model at all—Salmonella in the intestines, for example.

By Jan. 1, 2005, Dr. Apley hopes to present some of the system applications to reviewers and the project board of directors for input, so that by spring, he can make the applications available to the veterinary profession for feedback.

"One of the things I think is really neat about the system," he said, "is it's pointing out some places where we've done things this way for all these years, and we're just sure there had to be a reason somewhere—and there really isn't!